A disk drive is a data storage device that stores data in concentric tracks on a disk. Data is written to or read from the disk by spinning the disk about a central axis while positioning a transducer contained on read/write heads near a target track of the disk. During a read operation, data is transferred from the target track to an attached host through the transducer. During a write operation, data is transferred in the opposite direction.
For a number of years, it has been a common practice to build hard disk drives with a head parking arrangement, where the magnetic head is moved to a parked position when it is not in use. In the parked position, the head is aligned with a radially inner or radially outer edge portion of the hard disk, beyond the region of the disk where information is stored. The parked position keeps the heads safe from mechanical shock and vibration. The heads cannot be on the media unless it is spinning, or else they may become stuck there, and damage to the heads or media may occur.
In the case of a removable disk drive, the heads must also be kept in a safe place during disk insertion and removal, or else they may be damaged by moving parts, such as shutters and doors. Currently, additional sensors may added to a disk drive to determine if the heads are properly parked. However, adding sensors or other parts to a disk drive is undesirable as additional parts increase the overall cost and complexity of the drive.
What is needed is a disk drive that can determine if the heads of the drive are properly parked without adding costly sensors or parts to the drive. Preferably the drive would use a system that takes advantage of parts already needed on the drive for other functions.